1. Field of the Invention
The present invention relates to a ball retainer chain, a method of making the same, and a linear guide apparatus, in particular, the ball retainer chain retains a plurality of axially and serially balls arranged therein, and any two balls are separated at intervals, thereby permitting the ball retainer chain and the balls to run in a circulating motion within a recirculating passage of the linear guide apparatus.
2. Description of the Related Art
The conventional linear guide apparatus generally comprises a slider and a rail that is axially stretchable. The slider and the rail respectively provide at least one row of corresponding raceways. A series of balls is disposed between the raceways and is allowed contacting the raceways and roll thereon. The slider further provides a return passage and two turnaround channels disposed correspondent with each row of the raceways. The turnaround channels connect to the return passage and an end gate on the raceway for forming a recirculating passage. Whereby, the balls are able to enter the return passage from the raceway area through the turnaround channels, and then enter the raceway area again from the return passage through the turnaround channels. As a result, the balls are capable of cyclically traveling within the recirculating passage. Moreover, by means of the traveling of the balls, the slider would also unlimitedly move along the raceway on the rail.
In order to avoid any collision between any two balls, the slider further provides a ball retainer chain. Namely, a series of spacers are positioned between the balls and connected by a linking strip. Whereby, the spacers positioned between the balls would separate every two balls for preventing any collision. Thereby, the balls are positioned at intervals for the further circulation, and the slider would thence travel smoothly. A ball retainer chain issued by a Japanese unexamined patent publication No. 05-052217 directly inserts a ball into a resin mold for shaping an appropriate indentation to receive the ball. However, since the resin material readily contracts, the ball could not freely rotate within a hole provided by such ball retainer chain, and thence a resistance would be generated to adversely incur an uneven motion thereof.
Another ball retainer chain issued by a U.S. Pat. No. 5,988,883 employs a resin that changes its contracting rate after absorbing water or oil. Namely, an interstice between the balls and the spacers would be expanded after soaking for the balls to be freely rotated. However, the molding of such ball retainer chain has to insert balls into the mold, thereby incurring a more complicate molding means; the automation thereof is also intricate. In addition, since the spacers and the balls are densely combined with each other, the lack of the oil storage is emerged.
Another ball retainer chain issued by a US publication No. 2008-0025653 provides an upper-lower die to prevent an incomplete molding. Although some ragged edges would be still generated, the ball retainer chain would not be influenced and could still keep a smooth movement. However, such ball retainer chain could not allow the ball to be retained in the center of the hole by the spacer.
Another linear guide apparatus issued by an R.O.C. patent No. I294497 discloses at least two straightforward restricting surfaces respectively disposed at the front and the back of each separating portion. Wherein, an upper section and a lower section of each straightforward restricting surface individually form a flat-straight surface and a claw surface. Moreover, each two adjacent straightforward restricting surfaces are interlacedly disposed, and between each two adjacent separating portions an accommodation is formed for receiving the rolling element. Whereby, the periphery of each claw surface would restrict the balls to secure the rotation of the same therein. However, since the straightforward restricting surfaces on the separating portions are interlacedly disposed with each other, a sectional difference rather than an even surface is generated between the adjacent straightforward restricting surface and the claw surface. Additionally, each straightforward restricting surface is shaped by the mold from divergent directions, so ragged edges are readily generated at the place where the sectional difference occurs; therefore, the rolling element is subjected to be influenced and an unsmooth movement is incurred.